add 'show subscriber' command, alias for 'subscriber ... show'

When I wrote the osmo-hlr subscriber command, I failed to heed the common
'show foo' scheme and instead created a 'subscriber [...] show' command.
Relieve that weirdness by creating an alias that has 'show' at the start.

Arrange string macros so that the 'show subscriber' cmd doesn't end in a space
(the SUBSCR macro ends in a space ' ' to implicitly include the space to
commands like 'create', 'show', 'update').

Add the new command to test_nodes.vty and test_subscriber.vty.

Change-Id: I01ce9b0868302d40ed05c6a588316a194d6071e4
3 files changed